What is Fuel Feed System | Functions and Types.

To run an automobile engine, either a diesel engine or a petrol engine, the fuel from the fuel tank must reach by some means the engine cylinder. In a petrol engine, the petrol from the fuel tank reaches through the fuel pump, filter, and carburetor to the engine cylinder. In a diesel engine, the carburetor is not needed, the fuel is injected into the engine cylinder by an injector. In this article, I will discuss the fuel feed system in detail: 

Fuel feed system

What is fuel feed system

A fuel feed system is the most important and essential part of the engine. The fuel from the fuel tank is fed to the engine through various parts. A properly functioning fuel feed system is critical for the efficient operation and longevity of an engine. Manufacturers use the fuel feed system consists of the following components-

  1. Fuel tank
  2. Fuel pump
  3. Fuel filter
  4. Carburetor
  5. Intake manifold
  6. Fuel lines
  7. Fuel gauge.

Functions of Fuel feed system- 

The function of a fuel feed system is to feed the fuel to the engine to achieve optimal combustion.  In the fuel feed system, each and every component plays a great role in the operation of the system. The main functions of the fuel feed system are- 
  • It is used to store the fuel in the fuel tank. The tank may also include a fuel level sensor that sends signals to the vehicle’s instrument cluster to indicate the amount of fuel remaining in the tank.
  • It is used to supply the fuel to the engine to the required amount in proper condition. The fuel pump draws fuel from the tank and delivers it to the engine. There are two types of fuel pumps: mechanical and electric. Mechanical fuel pumps are typically found in older vehicles and are driven by the engine’s camshaft. Electric fuel pumps are more commonly used in modern vehicles and are powered by electricity. The fuel pump is responsible for creating the necessary pressure to deliver fuel to the engine.
  • The function of the fuel feed system is critical to the operation of an internal combustion engine. The engine requires the right amount of fuel at the right time to achieve optimal combustion. It also indicates to the driver the fuel level in the fuel tank. If the fuel feed system is not functioning properly, the engine may experience a range of problems.

Types of fuel feed systems- 

The fuel needs to be delivered to the engine for operation. The fuel from the fuel tank can be supplied to the engine cylinder by the following – 

Gravity fuel feed system- 

A gravity fuel feed system is a simple and basic fuel delivery system that relies on the force of gravity to deliver fuel from the fuel tank to the engine. In the gravity system of fuel feed, the fuel tank is mounted at a place higher than that of the carburetor. The fuel flows from the tank to the carburetor due to the gravitational force. Thus, the system does not require any fuel pump. It is a cheap and simple design. The fuel tank is directly connected to the carburetor. Scotters and motorcycles make use of this system. 


Pressure fuel feed system- 

In the pressure system, a pressure-sealed tank is used. The pressure is created in the tank by means of a separate air pump. For starting, the pump is primed by a cam which produces pressure in the tank and the fuel flows to the carburetor. In this system, the tank can be placed above or below the carburetor. 
Pressure fuel feed systems are commonly found in modern vehicles, where they provide better control over the fuel delivery to the engine, resulting in improved performance, fuel efficiency, and reduced emissions. They are also suitable for engines that require higher fuel flow rates.

Vacuum fuel feed system- 

In a vacuum system, the engine suction is used for sucking the fuel from the main tank to the auxiliary fuel tank from where it flows by gravity to the carburetor. The vacuum is created by the engine’s intake manifold, which draws in the air during the intake stroke and creates a vacuum in the manifold. The vacuum is then used to open the fuel valve in the carburetor, allowing fuel to be drawn into the engine.

Pump-type fuel feed system- 

In the pump system,, a fuel pump is used to feed the fuel from the fuel tank to the carburetor. The pump is driven either by the camshaft or electrically. In this system, the fuel tank can be placed at any suitable position in the vehicle. 
Pump fuel feed systems are commonly found in modern vehicles and some larger equipment where high fuel flow rates are required. It offers better fuel control and precision than vacuum and gravity fuel feed systems, resulting in improved fuel efficiency, better engine performance, and reduced emissions.

Fuel injection type fuel feed system- 

In a fuel injection system, a fuel injection pump is used in place of a carburetor. The fuel is atomized by means of a nozzle and then delivered into an air stream. A separate fuel injection system is used for each cylinder which controls the mixture under different load and speed conditions. This system is fully controlled by the ECU. 


A fuel feed system is necessary for automobiles for precise and perfect combustion of the fuel. The gravity, pressure, and vacuum systems of fuel feed are almost obsolete now. The pump system is used universally on motor vehicles. some gasoline engines use fuel injection systems. 
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